There are many reasons why an increasing number of people are classified as obese - and now racism could be one of them.

Frequent experiences of racism are associated with a higher risk of obesity among African American women, a new study claims.

Scientists found that women who were more frequently victimised for their race, were more likely to be obese.

Frequent experiences of racism are associated with a higher risk of obesity among African American women, a new study claims. Scientists found that women who were more frequently victimised for their race, were more likely to be obese. Here, a teenager in Virginia is examined in hospital before gastric band surgery

The study, by Slone Epidemiology Centre at Boston University, found the relationship between racism and obesity was strongest among women who reported consistently high experience of racism over a 12 year period.

The research was based on the Black Women's Health Study, which enrolled 59,000 African-American women in 1995 and has followed them since.

Scientists said that racism is a form of psychosocial stress that African Americans experience disproportionately.

It is thought that experiences of racism contribute to obesity. Data suggests that chronic exposure to stress can result in dysregulation of important neuroendocrine functions, (interactions between the nervous and endocrine systems) which can influence the accumulation of excess body fat.

The study found that women who reported everyday racism in and outside of work in surveys conducted in 1997 and 2009, were 69 per cent more likely to become obese compared to those in the lowest category

The participants were asked in 1997 and in 2009 to rate the frequency of ‘everyday’ experiences of racism, such as receiving poorer service in restaurants and if they had been treated unfairly because of their race in their job, in housing or by the police.

Researchers analysed the results of women under the age of 40 in 2009 because most adult weight gain occurs during the reproductive years.

They found that women in the highest category of reported everyday racism in both 1997 and 2009 were 69 per cent more likely to become obese compared to those in the lowest category.

Women who reported more lifetime racism were also at increased risk of obesity, according to the study, which was published in the American Journal of Epidemiology.

‘Experiences of racism may explain in part the high prevalence of obesity among African American women,’ said Yvette Cozier, assistant professor of epidemiology at Boston University who led the research.

She believes that workplace and community-based programmes to combat racism are an important component in strategies to prevent obesity, especially in high risk communities.

ARE WE BORN RACIST? CHILDREN AS YOUNG AS SEVEN MAKE JUDGEMENTS

Another new study found that a sample of mostly white American children think that black children feel less pain than white children.

Scientists from the University of Virginia found that children as young as seven hold the belief and their study, published in the British Journal of Developmental Psychology, builds on previous works on bias among adults involving pain perception.

They testest children at ages five, seven, and 10 by asking them to rate the severity of pain that they believed would be felt by other children of the same gender in different situations, such as bumping their head, or slamming a hand in a door.

When shown pictures of black children, the seven and 10-year-olds tended to rate the pain as being less severe than when they were shown pictures of white children.

‘Our research shows that a potentially very harmful bias in adults emerges during middle childhood, and appears to develop across childhood’ said Rebecca Dore, a PhD candidate in developmental psychology at the university.

She thinks the finding is important because many kinds of explicit biases emerge in early childhood - such as children wanting to play with friends of their own race - but those types of biases often decline in later childhood.

However, the racial bias in children’s perceptions of others’ pain appears to strengthen from early to late childhood.

‘Talking to children about racial issues early may be important for preventing the development of biases that could have consequences in adulthood,’ she said.